This invention relates to a method for reducing stress in animals, and a block for use in practicing the method. The invention is particularly useful for the reduction of tail biting and ear biting among pigs caused by stress in an overcrowded breeder during the fattening stage and the wearing period. The invention is further useful for reducing the incidence of cannibalism among poultry, and improving the feed conversion ratio and weight gain of cattle and swine.
Growth promotion of animals by feeding them powder, granules or pellets with added vitamins, minerals or fatty oils and molasses is known. (Jap. Pat. Unexam. Publ. No. 56-144059 and No. 58-47442.) Furthermore, in order to balance sodium for herbivora which are fed high potassium content grass, highly compressed sodium chloride blocks can be licked (Jap. Pat. Unexam. Publ. No. 55-26814). These prior known breeding methods are not for relieving stress in animals.
Stress syndromes of animals are caused by three primary factors, namely nutrients, circumstances and psychological factors, for example lack of a sufficient number of feeding vessels, insufficient water supply, noise, sudden change of bed temperature in animal barns, insufficient ventilation, high humidity of beds, overcrowded breeding and lack of exercise. Among these, overcrowded breeding is a serious problem. For example, in the case of overcrowded breeding of pigs, discomfort syndromes such as tail biting and ear biting occur. (Disease of pig: Kindai Publ. Co., p. 745, 1983) In order to prevent these stresses and for avoiding dullness in pigs, iron chains or used tires are hung for the pigs to bit, or straw bedding is supplied in the pigsty for biting. An increase in the number of stress syndromes in pigs can coincide with a period of introducing new breeding administratiOn systems and modern breeding methods, for example an expansion of the breeding scale, and automated centralized administration of the pigsty and the labor system are thought to affect the attitude and temper of pigs and may cause undesirable results. In the case of poultry, these conditions promote increased cannibalism (e.g. tail-pecking), and this cannibalism is a leading cause of death among poultry subject to these conditions. In the case of swine, cattle and poultry, these conditions decrease the animals' weight gain and increase the feed conversion ratio (feed intake/weight gain).